全文获取类型
收费全文 | 2085篇 |
免费 | 106篇 |
国内免费 | 306篇 |
专业分类
林业 | 140篇 |
农学 | 209篇 |
基础科学 | 215篇 |
345篇 | |
综合类 | 916篇 |
农作物 | 103篇 |
水产渔业 | 130篇 |
畜牧兽医 | 392篇 |
园艺 | 24篇 |
植物保护 | 23篇 |
出版年
2024年 | 15篇 |
2023年 | 28篇 |
2022年 | 57篇 |
2021年 | 81篇 |
2020年 | 85篇 |
2019年 | 118篇 |
2018年 | 67篇 |
2017年 | 103篇 |
2016年 | 142篇 |
2015年 | 99篇 |
2014年 | 128篇 |
2013年 | 121篇 |
2012年 | 209篇 |
2011年 | 195篇 |
2010年 | 137篇 |
2009年 | 167篇 |
2008年 | 111篇 |
2007年 | 111篇 |
2006年 | 90篇 |
2005年 | 80篇 |
2004年 | 66篇 |
2003年 | 53篇 |
2002年 | 35篇 |
2001年 | 34篇 |
2000年 | 29篇 |
1999年 | 20篇 |
1998年 | 18篇 |
1997年 | 21篇 |
1996年 | 5篇 |
1995年 | 12篇 |
1994年 | 13篇 |
1993年 | 12篇 |
1992年 | 6篇 |
1991年 | 9篇 |
1990年 | 5篇 |
1989年 | 5篇 |
1988年 | 2篇 |
1987年 | 3篇 |
1986年 | 2篇 |
1984年 | 1篇 |
1982年 | 1篇 |
1956年 | 1篇 |
排序方式: 共有2497条查询结果,搜索用时 31 毫秒
991.
利用6只1.0~1.5岁、体重(55.3±3.8)kg、装置永久性十二指肠和回肠瘘管的小尾寒羊公羊,收集十二指肠和回肠食糜试验的同时,进行消化代谢试验,研究在粗料型日粮(玉米秸秆67%)和精料型日粮(玉米秸秆30%)条件下添喂气溶胶OT(0.8 g/kg日粮)对绵羊自由采食和整体消化代谢的影响。结果表明,在粗料型日粮条件下添喂气溶胶OT,绵羊的干物质自由采食量增加30.7%(P0.01),干物质、有机物、粗蛋白(表观)消化率分别提高6.8%(P0.05),7.6%(P0.05),7.9%(P0.05),氮、钙和磷保留量分别增加49.1%(P0.01),30.8%(P0.01),53.4%(P0.01);在精料型日粮条件下添喂气溶胶OT,绵羊的干物质自由采食量增加23.7%(P0.01),绵羊的干物质、有机物、粗蛋白(表观)消化率分别提高3.4%(P0.05),4.1%(P0.05),7.7%(P0.05),氮、钙和磷保留量分别增加29.5%(P0.01),49.3%(P0.01),24.2%(P0.01)。添喂气溶胶OT可以提高绵羊自由采食量,提高消化率,增加氮保留,这种作用在粗料型日粮条件下更显著。 相似文献
992.
选取平均体重分别为(48.5±2.1),(47.6±3.2)kg的2.5~3.5岁空怀小尾寒羊和新疆策勒黑羊母羊各6只,自由采食粉碎玉米秸秆占70%的粗料型日粮,以自身对照设计,比较添喂气溶胶OT(0.8 g/kg日粮)对小尾寒羊、策勒黑羊消化代谢的影响。结果表明,添喂气溶胶后小尾寒羊和策勒黑羊的干物质自由采食量分别提高25.2%(P〈0.01)和25.3%(P〈0.01);干物质表观消化率分别降低12.0%(P〉0.05)和8.3%(P〉0.05);有机物表观消化率分别降低7.9%(P〉0.05)和6.6%(P〉0.05);粗蛋白表观消化率分别降低3.2%(P〈0.05)和4.3%(P〉0.05);能量表观消化率分别降低12.0%(P〉0.05)和8.3%(P〉0.05);纤维素消化率分别提高1.1%(P〉0.05)和2.3%(P〉0.05);半纤维素消化率分别提高2.3%(P〉0.05)和6.2%(P〉0.05);氮保留分别增加13.7%(P〉0.05)和11.1%(P〉0.05);钙保留分别增加25.2%(P〈0.01)和21.2%(P〈0.05);磷保留分别增加24.3%(P〈0.05)和18.2%(P〉0.05)。添喂气溶胶OT可提高绵羊自由采食量和消化量,改善绵羊的消化代谢,但在小尾寒羊和新疆策勒黑羊母羊间没有显著差异。 相似文献
993.
张荣 《国际沙棘研究与开发》2014,(3):11-14
沙棘果油样品经微波消解处理,采用电感耦合等离子体质谱法测定所得样品溶液中铁、硒、锌、钾、钠、钙、镁、铜、锰、铅、砷、汞、镉等13种微量元素的含量。使用动态反应池技术消除了多原子离子对部分被测元素的干扰。方法快速准确、灵敏度高,加标回收率在96.1%~101%之间,相对标准偏差小于3%。 相似文献
994.
995.
为研究莫能菌素饲喂肉牛后对日粮养分消化代谢及瘤胃甲烷排放的影响,选用12月龄左右、健康、发育正常的西门塔尔牛48头,按随机设计分成4组,对照组试验牛饲喂由混合精料与玉米秸秆所组成的基础饲粮,其精粗比45∶55,处理1、处理2和处理3组分别在基础日粮基础上添加100、200和300 mg·d-1的莫能菌素,进行为期70 d的试验。结果表明,处理2和处理3的粗蛋白消化率和采食氮显著高于对照组(P0.05),甲烷能显著低于对照组(P0.05);处理2和处理3的粪氮和尿氮显著低于对照组和处理1(P0.05),而可消化氮和沉积氮显著高于对照组和处理1(P0.05);处理组的氮排泄/采食氮、磷排泄/采食磷显著低于对照组(P0.05)。综合以上各项指标,当莫能菌素的添加量为300 mg·d-1时,日粮中粗蛋白的消化率、氮利用率提高,氮、磷和甲烷排放降低。 相似文献
996.
A. G. Goachet P. Harris C. Philippeau V. Julliand 《Journal of animal physiology and animal nutrition》2014,98(6):1081-1087
This study aimed at evaluating, in previously inactive Standardbreds horses, the effect of 5 weeks of an exercise training programme on nutrient digestibility and faecal fermentative parameters (FFPs). As an increase in digestibility had previously been reported in trained endurance horses, we hypothesized that similar results would be found in horses being trained for other types of exercise on a different type of diet. After 3 weeks of dietary adaptation, a digestibility trial (DT1) was undertaken, over 3 days, in eight untrained Standardbreds with a fresh faecal sample being collected on the second day for FFP determinations. Six of the eight horses undertook a training programme, and after 5 weeks of exercise, the DT and the FFP measurements were then repeated (DT2). DT2 began after 3 days of inactivity. The same natural meadow hay (H) and pelleted complementary feed (CF) were fed throughout. For 5 days before the DTs, horses were fed 2.1% BW on a dry matter basis (55:45 ratio H:CF). Body weight and body condition score remained constant. Apparent digestibility of dry matter, organic matter, neutral detergent fibre, hemicellulose, crude protein and gross energy, as well as faecal total volatile fatty acids (VFA), acetate and propionate concentrations were significantly (p < 0.05) higher at DT2 than at DT1. A 5‐week exercise programme had a positive impact on nutrient digestibility and FFP. Training may improve dietary energy supply, in particular via increased hindgut VFA production. The potential improvement of digestive efficiency with training should be taken into account when formulating nutritional recommendations for the exercising horse, particularly when performing light work, which is low‐intensity exercise for 1–3 h per week. 相似文献
997.
Vervuert I Voigt K Hollands T Cuddeford D Coenen M 《Journal of animal physiology and animal nutrition》2009,93(5):631-638
The aim of this study was to investigate the effects of feeding oats alone before or after feeding chopped alfalfa or, in admixture with the alfalfa on the glycaemic and insulinaemic responses of horses as well as post-prandial breath hydrogen and methane excretion. Horses were fed in a randomized order, chopped alfalfa as a source of dietary fibre and unprocessed oats as a source of starch. Chopped alfalfa intake was adjusted to a crude fibre intake of 0.5 g/kg bodyweight (BW) per meal and the oats intake was adjusted to a starch intake of 2 g/kg BW per meal. The feeds were offered in three different ways: (i) alfalfa followed by oats (A/O), (ii) oats followed by alfalfa (O/A) or (iii) a mixture of alfalfa and oats (A + O). Oats alone were used as a control. Blood and breath were collected after the test meal was fed at the end of a 11.5-h overnight fast following a 10-day acclimatization period. The highest glycaemic and insulinaemic responses were measured when the A/O and O/A diets orders were fed, whereas most hydrogen was produced after feeding oats alone. It was concluded that adding alfalfa chaff to a meal of oats prolonged the pre-caecal digestion of starch, but there was no evidence for any effect on pre-caecal starch digestibility. 相似文献
998.
以5月龄左右重庆黑山羊为试验动物,配制了粗蛋白质水平分别为8.23%、10.42%和12.52%的饲粮,进行了消化代谢试验和瘤胃降解试验。结果表明:随着饲粮中粗蛋白质水平的提高,各组间的干物质消化率、粗蛋白质消化率、氮沉积率、中性洗涤纤维消化率、酸性洗涤纤维消化率、粗纤维消化率之间的差异均不显著(P>0.05)。随着饲粮中粗蛋白质水平的提高,瘤胃内中性洗涤纤维的降解率在各个时间点变化不明显(P>0.05);酸性洗涤纤维的降解率在6h及以前降低(P<0.05),之后接近;干物质的降解率在6h及以前提高(P<0.05),之后接近;有机物的降解率在6h提高(P<0.05),之后接近;粗蛋白质降解率在12h及以前提高(P<0.05),之后接近。 相似文献
999.
1000.